This invention relates to a heater follower apparatus for hot melt dispensers and more particularly to an integrally fabricated heater follower plate for hot melt dispensers.
In recent years, various different materials that are now commonly called hot melt materials have been developed. Hot materials are generally either unpumpable solids or high viscosity unpumpable liquids at or below a given temperature. There are many different types of hot metal materials and these various different hot melt materials require different temperatures to convert them from a solid to a pumpable liquid to from a highly viscous unpumpable liquid to a less viscous pumpable liquid.
While hot melt materials have numerous potential uses, these materials have not been used as widely as anticipated by persons knowledgeable in the field, because of problems encountered in dispensing the materials at a suitable rate, particularly the high viscosity hot melt materials. While smaller containers have been used, producers of hot melt materials generally store and transport the hot melt materials to the consumer in 55 gallons drums. Several different types of dispensers for heating and dispensing hot melt materials from their containers have been developed. One type of dispenser available on the market utilizes a follower plate in combination with a heater. The follower plate and the heater are lowered into the container of hot melt material and the heater is then energized to melt the hot melt material. As the hot metal material is melted, it is dispensed from its container, generally by means of a pump that pumps the material out of the container through an opening provided in the follower plate. As the material is dispensed out of the container, the heater and follower plate move down into the container. Such hot metal dispensers using a separate heater and follower plate are disclosed, for example, in U.S. Pat. No. 3,282,469 to Skonberg and U.S. Pat. No. 3,637,111 to McCreary. In the said Skonberg patent the heater is secured to the bottom of the follower plate and an insulator is placed between the follwer plate and the heater. In the McCreary patent. the heater is located below and spaced apart from the follower plate. There are, of course, other hot melt dispensers on the market.
I first became involved with hot melt materials and dispensers when I was working on a project relating to insulated widow panes. The material being used was a highly viscous hot melt material. I was unable to obtain a dispensing rate suitable for my purposes with the prior art dispenser that I was using.
It became readily apparent, that in order to dispense the hot melt material at a rate suitable for my purposes, I had to have dispensing apparatus that melted the hot melt material at a suitable rate without scorching or burning the material. After considerable effort, I developed an integrally fabricated heater follower plate that upon testing, melted the material at a suitable rate for my purposes. That is, my heater follower plate melted the material at such a rate that is could be dispensed at the required rate. This heater follower plate is disclosed in my U.S. Pat. No. 3,982,669. The apparatus disclosed in my said U.S. Pat. No. 3,982,669 provided a melt rate and dispensing rate that was appreciably greater than I had been able to obtain previously.
Since my initial work with hot melt materials, I have conducted dispensing tests with a variety of different hot melt materials usually at the request of manufacturers of the hot melt materials. While conducting those tests, I continued to experiment with ways to increase the dispensing rate and with ways to more economically produce my integral heater follower plate. The integral heater follower plate of this invention is a product of that testing and experimentation.
With the integral heater follower plate of this invention, the melt rate, and therefore the dispensing rate, has been appreciably increased over the melt rate I obtained with the integral heater follower plate disclosed in my said U.S. Pat. No. 3,982,669.